(1) Field of the Invention
The present invention relates to a light-exposing device for manufacturing a semiconductor device. More particularly, it relates to a light-exposing device for manufacturing a semiconductor device which is capable of forming patterns on a reticle consecutively by creating the superposition of the light-exposing energy and projecting the patterns on the reticle to a plate, using an extra optical system condensing light passing through a blind, in a stitching process through which a screen is exposed to light by pattern synthesis.
(2) Description of the Related Art
In order to form an electronic circuit on a semiconductor wafer or a glass substrate of a liquid crystal display device, patterns on which electronic circuits are formed are required. A glass plate having such patterns is referred to as a reticle or mask.
A light-exposing device projects the pattern on the reticle onto a semiconductor wafer or a substrate of a liquid crystal display device. When the size of a display is beyond the light-exposing range of a projection lens in the steps in the manufacturing of a liquid crystal display device, a screen synthesis is carried out by dividing the display screen and selectively exposing it to light.
To form patterns on the reticle successively for the screen synthesis in manufacturing order, the patterns on the reticle other than the pattern that is being used in the processing, have to be covered artificially. A blind is used to cover the rest of the patterns artificially from the light in manufacturing order to project the patterns on the reticle as stated above.
Controlling the above-mentioned blind and selectively exposing the pattern on the reticle to light is a stitching process, which acts as an important factor for improving the productivity in the steps of exposing the pattern of the liquid crystal display device to light.
As illustrated in FIG. 1, a conventional light-exposing device includes: a light source 1 having an ultra high pressure mercury-arc lamp 1; a reflector 2; a condenser lens 3; a blind 4; a reticle 5; a projection lens 6; and a plate 7.
A dot of light produced by the light source 1 is diffused into a surface of light by the reflector 2. The surface of light impinges on the condenser lens 3. The condenser lens 3 condenses the surface of light and irradiates it on the reticle 5 having patterns.
The blind 4 covers the reticle 5 except for the pattern to be exposed. Accordingly, light from the condenser lens 3 is irradiated on the pattern of the reticle 5 to be exposed to light through the blind 4. The projection lens 6 projects the pattern on the reticle 5 not covered by the blind 4 onto the surface of the plate 7. A resist on the plate 7 is exposed to light influenced by the pattern on the reticle 5.
At this point, the light-exposing energy irradiated on each pattern on the reticle 5 is distributed only to the pattern to be exposed to light by the light irradiated through the blind 4, as illustrated in FIG. 4, and thus the light-exposing energy is not superimposed.
When the pattern on the reticle 5 is formed as shown in FIG. 2, the size of the blind 4 that covers the remaining parts other than the pattern to be exposed to light is adjusted to be bigger than the pattern that is exposed to light. That is, since there is a possibility that the quality of the pattern exposed to light may be deteriorated by the dispersion of light irradiated on the edge of the blind 4, the blind 4 is adjusted so that the part to which the light is irradiated may be bigger than the pattern exposed to light on the reticle 5.
Accordingly, while the pattern on the plate 7 is projected contiguously without any space as illustrated in FIG. 3, the pattern to be exposed to light on the reticle 5 has to be formed to keep a regular interval as illustrated in FIG. 2.
Thus, with the conventional technique, an efficiently usable area in the reticle is reduced, and precision of location for keeping interval with each pattern when a pattern is formed has to be considered.
Further, there is a possibility that when a pattern projected on a plate is not located precisely, the exposure to light between the patterns may be excessive or lack to result in deterioration of product.